This invention relates generally to biometric systems and methods and, in particular, to systems that identify a speaker by the automatic recognition of the speaker""s voice and, more particularly, to a wireless telecommunications system employing voice recognition.
Biometric systems typically employ and measure some physical characteristic of a particular individual to uniquely identify that individual. The characteristic could be, by example, a fingerprint, a retinal pattern, or a voice pattern. The use of this latter characteristic is especially attractive for those systems that already include a microphone, such as telecommunications system, as no hardware expense may need to be incurred in order to implement the identification system. After having uniquely identified a speaker as being a particular, authorized individual, the system can then grant the speaker access to some location or to some resource. That is, this type of biometric system can be viewed as an electronic, voice actuated lock.
One problem that arises in many such systems is that the system is trained to recognize a particular speaker using a limited set of spoken words. For example, the speaker may be expected to say his or her name, and/or some predetermined password. While this approach may be suitable for many applications, in other applications the limited set of words used for identification may not be desirable, and may in fact lead some other persons to attempt to defeat the voice recognition-based biometric system. For example, a person attempting to defeat the system may simply surreptitiously tape record a person speaking the word or words that the biometric system expects to be spoken, and then play back the authorized person""s speech to the voice input transducer of the biometric system.
It is well known in the mobile telecommunications art to provide a mobile telephone, such as a vehicle-installed cellular telephone, with a voice recognition capability in order to replace or augment the normal user input device(s). For example, the user can dial a number by speaking the digits, or by speaking a name having a stored telephone number. Some commands could be given to the telephone in the same manner.
In general, current user identification methods are based on measuring one static feature: e.g., a written password, a spoken password (voice recognition), a fingerprint, an image of the eye and so on. In the identifying situation the user knows what is measured and how.
It is an object of this invention to provide an improved biometric system, in particular a voice actuated recognition system, that relies on a random set of words and or images.
It is a further object of this invention to provide a mobile station having a speech transducer, and a method and apparatus to authenticate or authorize a user of a wireless telecommunication system to operate in, or through, or with a resource reachable through the wireless telecommunication system, only if the user""s speech characteristics match pre-stored characteristics associated with word selected randomly from a training set of words.
The foregoing and other problems are overcome and the objects of the invention are realized by methods and apparatus in accordance with embodiments of this invention.
According to this invention, when a user enters an identifying situation he or she does not know beforehand what the identification stimulus will be and, thus, what the user""s reaction or response will be. Using current technology a most straightforward way to implement the invention is with voice recognition. In this case the user is presented with a voice stimulus, or a text stimulus, or a graphical image stimulus, and the user reacts with his or her voice. The stimulus can be direct (e.g., the user speaks a displayed word) or indirect (e.g., the user responds to a question that only the user knows the answer to). Since even the correct user does not know beforehand the details of the identification situation, it becomes very difficult or impossible to know beforehand what the expected correct response will be.
A method is disclosed to authorize or authenticate a user of a wireless telecommunication system, and includes steps of (a) selecting a word at random from a set of reference words, or synthesizing a random reference word; (b) prompting the user to speak the reference word; and (c) authenticating the user to operate in, or through, or with a resource reachable through the wireless telecommunication system, only if the user""s speech characteristics match predetermined characteristics associated with the reference word.
In one embodiment the steps of selecting or synthesizing, prompting, and authenticating are performed in a mobile station having a speech transducer for inputting the user""s speech, while in another embodiment at least one of the steps of selecting or synthesizing, prompting, and authenticating are performed in a wireless telecommunications network that is coupled between the mobile station and a telephone network. In yet another embodiment at least one of the steps of selecting or synthesizing, prompting, and authenticating are performed in a data communications network resource that is coupled through a data communications network, such as the Internet, and the wireless telecommunications network to the mobile station.
The step of prompting may include a step of displaying alphanumeric text and/or a graphical image to the user using a display of the mobile station.